Chain hoists are used for lifting and lowering items, as we all pulling loads. To do so, a link chain, in particular a circular steel chain or a round profile chain is used. Usually, a chain hoist comprises a holder, for example a hook, which can be suspended from a scaffolding. The hook is adjoined by a chain hoist housing with a lifting motor that drives a chain sprocket over which the chain moves. A load hook is arranged on the free end of the chain. The housing comprises an opening with an adjoining channel through which the part of the chain disposed for bearing the load moves onto the chain sprocket. Such a channel frequently has a cruciform cross-section in order to guide a link chain that consists of several, preferably equal, chain links that alternately come into engagement with each other while oriented in transverse direction relative to each other. The channel acts as a controlled guide of the chain.
Particular chain hoists for stage technology, also referred to as rigger hoists, have a design that is inverted with respect to an embodiment described hereinabove. In that case, the lose end of the chain is disposed for fastening the chain hoist at a desired height. The hook provided on the housing is disposed for taking up the load. During operation, the load, together with the housing on the chain, is pulled up or lowered.
When the chain hoist is dismantled after its use, the housing is placed on the stage floor or put on a trestle there, and the chain that is fastened at a given height is loosened and let down onto the housing. In doing so, the chain comes to rest on the surface of the housing—in the region of the opening, i.e., the mouth opening of the channel having the cruciform cross-section. The hoisting motor is used to retract the chain through the housing into the chain storage. In doing so, it may happen that a chain link positions itself sideways in front of the channel and thus blocks the continued retraction of the chain. With great effort, the operator has to then manually eliminate the blockage. The retraction process is tedious, and the operator is occupied during the entire retraction process.
To solve this technical problem, German Patent 1 228 384 suggests a guide channel that widens toward the housing surface. Therefore, a space is created in one end-side section of the channel, in which space a sideways positioned chain link may rotate before it is guided in a retraction direction through the tapering channel. The torque required for rotation is applied to the sideways positioned chain link by the subsequent chain link that strikes the sideways positioned chain link due to the transverse orientation.